As the number of older people increases, the number of people who experience dementia before they die is also likely to increase, according to a new study. The research, spearheaded by Professor Carol Brayne at the University of Cambridge, has shown that factors believed to protect against dementia at earlier stages in life may not provide protection from dementia at the end of life.
Previous studies examined risk of dementia over a specified time period or at a particular age but not just before death. Thus it was not known whether factors found to reduce the risk of developing dementia earlier in life would provide protection until the end of life. For example, previous research studies have consistently suggested the risk of dementia is reduced for people with higher levels of education and social class, but whether this affects the risk of having dementia by time of death had not been investigated (partly because most studies do not follow individuals over very lengthy periods).
The study followed populations aged 65 years and over for ten years and found that reducing risk for dementia at a given age is likely to lead to further extension of life, thus the cumulative risk of dementia at death (even in populations at lower risk for given ages) will remain high. Ageing of populations, due to better nutrition and improved health care, is likely to result in an increase in the number of people dying with dementia and severe cognitive impairment even in the presence of preventative programmes.
For this study, funded by the Medical Research Council, the prevalences of dementia and severe cognitive impairment were estimated by age, sex, social class and education to examine whether any different patterns emerged. Overall 30% of individuals who died have experienced dementia in their last year of life. There was a strong increasing trend with age from 6% for those aged 65-69 to 58% for those aged 95 and above.
The study also found that women were more likely to develop dementia before death than men (even after taking into account that women live longer than men). A higher level of education and belonging to a higher social class were associated with only a slightly lower prevalence of dementia before death.
Professor Brayne, from the Department of Public Health and Primary Care at the Institute of Public Health, said, ?Policy development and research for dementia must address the needs of individuals who will continue to experience these conditions before death, particularly with regard to long term care, support for informal care givers and appropriate palliative care options.?
Dr Fiona Matthews, at the MRC Biostatistics Unit, said, ?With increased survival into older age, population levels of dementia immediately preceding death will be a public concern”.